What is difference between photography and holography ?
System of photography, using neither a camera not lens, in which laser beams create an interference patter recorded directly on appropriate light sensitive sheet film or plates. After processing, viewing the image by the light of a laser gives a three dimensional image. It is the science of producing holograms; it is a form of photography that allows an image to be recorded in three dimensions. The technique of holography can also be used to optically store, retrieve, and process information .
Why laser is used for producing hologram ?
The object and the reference beams must be able to produce an interference pattern that is stable during the time in which the holographic recording is made. To do this, they must have the same frequency and the same relative phase during this time, that is, they must be mutually coherent. Many laser beams satisfy this condition, and lasers have been used to make holograms since their invention .
What is laser ?
Laser (Light Amplification by Stimulated Emission of Radiation) is a highly concentrated, powerful beam of light that does not exist naturally, but may be produced in various mediums, using a variety of techniques. Lasers were invented as part of a scientific exploration of light and electromagnetism.
What is laser coherence ?
What is diffraction ?
Diffraction refers to various phenomena which occur when a wave encounters an obstacle.
What is interaction ?
The physical effects of two or many waves are interaction.